Simulation of Scoliosis Treatment Using a Brace

Abstract

Ivo Maoík M.D. has treated many child patients with scoliosis at the "Centre for Locomotor Defects", Olšanská 7, 130 00 Prague 3. The author has cooperated with him, and composed the computer program for the spine stress state under brace effects and for simulating scoliosis treatment. The program simulates the spinal curve remodelling in time for a specific child patients, and the algorithm for stress state calculation and treatment simulation is given.Orthopaedists in the Czech Republic use Cheneau-type or Cerny-type corrective braces. The brace exerts force effects on the skeleton of a child. The brace is made individually for each patient, in the following way: first, a negative plaster form of the child`s trunk is made, and then the positive plaster form is created. The orthopaedist determines the places where brace has to load the patient`s trunk, and the plaster form deepened in these places on the basis of his advice. The laminate brace made according to this plaster form constricts the child`s trunk (like a tight shoe).This paper shows how the stress state is determined in vertebrae and in inter-vertebral discs, and the solution of spinal curvature correction under brace force effects for a specific child patient. The project aims to find the dependence of the activation and velocity of spinal curvature correction in the spinal stress state for many patients. The paper shows the computing algorithms for spinal deformations and the stress state under brace force effects, and a simulation of spinal curvature correction.Spinal curvature is determined according to measured values on an X-ray of a patient before a brace is applied. The stress state in the spine and the spinal deformation are investigated by the finite element method as beam (spine) in an elastic ground (soft tissue). Two algorithms are used. The first algorithm deals with the spine above and below the soft tissues, and it is loaded by given displacements of the trunk surface. The second algorithm determines from the X-ray of a patient with and without a brace the spine deformation and the spine stress state, and the necessary trunk surface displacement is determined from this deformation.The calculation algorithm and parameters were compared with contest of treatment. The trunk surface load was checked by sensor that plates were placed into the braces to measure the load values between the brace and the surface of the child. The simulation program assesses the spinal curvature correction according to the spinal curvature type, the spinal stress state and the period of time for which the brace will be applied.